Microsoft Corp.'s move to release three of its drivers to Linux, however technically modest it may be, could put pressure on other closed-source vendors to follow suit.

The uneven availability of drivers for Linux has long contributed to the open-source operating system's forbidding reputation among non-techies, and -- despite its free price tag -- to its slow growth.

According to Greg Kroah-Hartman, a longtime Linux developer for Novell Inc. and the head of the Linux Driver Project, Linux today "supports hundreds of thousands of drivers."

"We support more devices than any other OS ever has," he said. Citing the announcement last month that the coming USB 3.0 technology will be supported by Linux first, Kroah-Hartman said "for huge classes of devices, we usually get drivers first."

At the same time, Kroah-Hartman conceded that Linux users still have a "harder time" getting drivers for some "brand new devices." That's because hardware vendors don't prioritize support for Linux due to its small desktop market share.

Moreover, some vendors who do release Linux drivers decline to make them open-source. Doing so would allow the drivers to be included in the Linux kernel, making the installation process much smoother for users. It would also make it possible for outside developers to tinker with and fix them.

Microsoft's drivers, which help Linux virtual machines run better under its own Hyper-V virtualization software, are already available for enterprises to add as a patch, and will be available in several months via the next major update of the Linux kernel, Kroah-Hartman said.

"This shows that their customers have been asking to run Linux," he said.

It also shows, in a posting to Slashdot by Sam Ramji, Microsoft's head of open-source strategy, that the company is not trying to undermine Linux or bolster its 2006 claim that Linux violated its patents.

"Our use of the GPL v2.0 license, as requested by the Linux community, means we will not charge a royalty or assert any patents covering the driver code we are contributing," he wrote.